The present invention relates to hearing aids. More particularly, it may relate to a hearing aid system that may comprise a charger and a rechargeable hearing aid; wherein the hearing aid may be optically or inductively recharged.
The rechargeable hearing aid may utilize any conventional rechargeable battery. However, preferably, the rechargeable hearing aid may utilize a high energy rechargeable battery that may comprise at least one high energy rechargeable cell, such as: (a) a NiMH (nickel metal-hydride) rechargeable cell; or (b) a lithium based rechargeable cell.
As used herein, the generic term "lithium based rechargeable cell (or battery)" may be defined as an aqueous or non-aqueous cell or battery in which at least one of the Faradaic half cell reactions includes lithium ions as reactants and/or products. In this context, non-aqueous means that the electrolyte does not contain a significant amount of water. In addition, as used herein, the "lithium based rechargeable cell (or battery)" may be classified as either a lithium rechargeable cell (or battery) (i.e., one having a lithium metal or a lithium alloy anode); or as a lithium-ion rechargeable cell (or battery) (i.e., one having no significant amounts of metallic lithium in its anode). Further, the lithium based rechargeable cell (or battery) may have a solid electrolyte in the form of a polymer or gel; and the lithium-ion rechargeable cell (or battery) may have either a liquid electrolyte, or a solid electrolyte in the form of a polymer or gel. In this context, the polymer electrolyte may be either a true polymer, or the polymer may be plasticized or gelled with the addition of at least one low molecular weight organic liquid.
The materials and the chemical reactions in the high energy NiMH and lithium based rechargeable cells and batteries described herein are all conventional.
However, each improved, high energy, rechargeable battery that is described herein may have a novel cell stack design for maximizing the surface area of its cathode and anode, to reduce the battery's impedance, while simultaneously minimizing the battery's overall size or volume. The rechargeable hearing aid may be provided with a DC to DC voltage regulating circuit to help match the high energy rechargeable battery's output voltage the input voltage required by the hearing aid's audio amplifier and related circuitry, and to help provide high current during transients due to loud sounds.